Documentation of plural rules
This is the thread's initial revision.
I have drafted a list of Mediawiki plural rules for all languages. I would be grateful if a translator could check that the rules for Arabic are correctly recorded in the list. If I have made a mistake please go ahead and correct it.
I see that you have got a note of the code for the Arabic Mediawiki plural rules on the arabic project page. However, it could be useful to explain the rules in Arabic, or in Arabic and English, for the benefit of any future new translators who, like me, struggle to understand code. You could also consider explaining how Arabic plural works in projects using CLDR or gettext.